Ship surfaces exposed to seawater are inclined to settlement by animal and plant organisms. The biological process, which is termed fouling, can result in the formation of a thick and hard crust that poses several problems in relation to maintenance, fuel consumption, and operational availability of ocean-going ships. Various ways of avoiding the fouling have been tried, but presently fouling is fought by the use of so-called antifouling paints, which slowly release biocides into the seawater.
In modern paints used for fouling control on commercial ships/vessels polishing is an essential feature ensuring that the biocide concentration at the surface is sufficient over time, and that the biofilm/macrofouling is minimized. In most paints the binder system polish slower than required for an effective diminishing of the fouling. The desired polishing rate is achieved by introduction of pigments and extenders/fillers in the paint. In commercial anti-fouling paints Cu2O, Cuprous oxide, and/or ZnO, Zinc oxide is used to enhance polishing control. The restrictions on use of biocides in paints have placed the use of Cu and Zn under pressure, since Cu constitutes a permanent biocide load on the environment and Zn is bioaccumulating. It is therefore of interest to find suitable replacements for Cu and Zn compounds that might provide the same favorable polishing rates.